The objectives of this research are as follows: To delineate the ultrastructure of the normal microcirculation in human skin. Microcirculation is defined to include both blood and lymphatic vessels. Psoriatic lesions in various stages of development and regression will be studied by electron microscopy to determine the nature of the vascular abnormalities noted by light microscopy, and whether these abnormalities precede or come after the epidermal hyperplasia of the disease. Telangiectasias of various types which indicate the presence of a systemic disease will be studied to determine their three dimensional configurations by cleared whole mounts of skin. The type of abnormal vessel present in the malformation will be studied by electron microscopy. The dermal vessels in diabetic skin will be studied by electron microscopy to determine whether a microangiopathy also exists in this organ as it is reputed for the eye, kidney and skeletal muscle.